A little more than a week after entering the concussion protocol and four days after missing his first game of the season, the Indianapolis Colts’ franchise quarterback returned to the practice field — an optimistic sign he could play next Monday night against the New York Jets.

“You have to be prudent with your brain, cautious is maybe the wrong word,” Luck said. “There’s a protocol for a reason and we have to do this by the book. I believe I have and the doctors and trainers have done a good job of sort of holding my hand to get through this process.”

Luck complained of concussion-like symptoms following a Nov. 20 win over Tennessee.

It wasn’t immediately clear when Luck was injured and he shed no additional light on what happened during his first interview since getting hurt. He also said it was the first time he’s been diagnosed with a concussion.

Coach Chuck Pagano acknowledged Monday that Luck had already cleared several steps of the protocol and is expected to take the next one when he returns to a full practice Wednesday.

If Luck does well enough, an independent doctor could subsequently clear Luck to play in next week’s game against the Jets (3-8).

Luck’s backup, the rarely used Scott Tolzien , struggled in Thursday’s loss to the Pittsburgh Steelers.

When word spread around the Colts’ locker room that Luck could return Monday night, the news was welcomed.

“Scott did a great job, but any time you can be healthy as an offense you have a chance to be successful,” center Ryan Kelly said.

Kelly missed most of Thursday’s game with a left shoulder injury and is hopeful of returning at the Jets. Receiver T.Y. Hilton (lower back) and outside linebacker Robert Mathis (biceps) also did not finish the game.

If Luck, Kelly, Hilton and safety Clayton Geathers (concussion) all return this week, the timing couldn’t be better.

Indy (5-6) needs to string together wins over the final five weeks to chase down AFC South leader Houston (6-5) and second-place Tennessee (6-6). The Colts already swept both meetings with the Titans this season.

The reeling Jets have lost three straight. The Colts still have home games against the Texans and Jacksonville and road trips to Minnesota and Oakland.

Luck gives Indy the best chance to make up ground.

The Colts missed the postseason last season for the first time in four years and they haven’t missed the playoffs in back-to-back seasons since 1997 and 1998.

But staying healthy the past two seasons has been difficult for Luck.

He’s already been sacked a league-high 35 times and been hit several more times this season, before sitting out Thursday night.

In 2015, Luck spent more than half the season on the sideline with a variety of injuries including a lacerated kidney that cost him the final seven games. The Colts went 6-3 in Luck’s absence.

The difference this season is that Indy doesn’t have a longtime veteran with Super Bowl experience to bail them out, so they need Luck to continue lining up, getting up and making plays over this final stretch.

And nobody knows it better than Luck.

“It’s no fun (sitting out), but once you’re out, you have to do what you can to help your team,” Luck said. “I feel great. I’m 100 percent. I’m ready to go.”

NOTES:

Pagano was asked whether Mathis was considered day to day after the long weekend. Pagano responded: “Yeah, you could say that.”

Outside linebacker Trent Cole, who has been on injured reserve, returned to the practice field Monday but has not yet been activated.